From: Arnd Bergmann <[email protected]>
Date: Fri, 20 Jun 2025 13:11:17 +0200

> From: Arnd Bergmann <[email protected]>
> 
> With large values of CONFIG_NR_CPUS, three Intel ethernet drivers fail to
> compile like:
> 
> In function ‘i40e_free_q_vector’,
>     inlined from ‘i40e_vsi_alloc_q_vectors’ at 
> drivers/net/ethernet/intel/i40e/i40e_main.c:12112:3:
>   571 |         _compiletime_assert(condition, msg, __compiletime_assert_, 
> __COUNTER__)
> include/linux/rcupdate.h:1084:17: note: in expansion of macro ‘BUILD_BUG_ON’
>  1084 |                 BUILD_BUG_ON(offsetof(typeof(*(ptr)), rhf) >= 4096);  
>   \
> drivers/net/ethernet/intel/i40e/i40e_main.c:5113:9: note: in expansion of 
> macro ‘kfree_rcu’
>  5113 |         kfree_rcu(q_vector, rcu);
>       |         ^~~~~~~~~
> 
> The problem is that the 'rcu' member in 'q_vector' is too far from the start
> of the structure. Move this member before the CPU mask instead, in all three
> drivers.
> 
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
>  drivers/net/ethernet/intel/fm10k/fm10k.h | 2 +-
>  drivers/net/ethernet/intel/i40e/i40e.h   | 2 +-
>  drivers/net/ethernet/intel/ixgbe/ixgbe.h | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/fm10k/fm10k.h 
> b/drivers/net/ethernet/intel/fm10k/fm10k.h
> index 6119a4108838..757a6fd81b7b 100644
> --- a/drivers/net/ethernet/intel/fm10k/fm10k.h
> +++ b/drivers/net/ethernet/intel/fm10k/fm10k.h
> @@ -187,6 +187,7 @@ struct fm10k_q_vector {
>       u32 __iomem *itr;       /* pointer to ITR register for this vector */
>       u16 v_idx;              /* index of q_vector within interface array */
>       struct fm10k_ring_container rx, tx;
> +     struct rcu_head rcu;    /* to avoid race with update stats on free */
>  
>       struct napi_struct napi;

I'd place it *after* ::napi as the latter is hot and better to still be
near rx/tx etc.

Same for the rest of the drivers.

Thanks,
Olek

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